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Singular spectrum analysis – an automatic detection technique for mean scatterer spacing estimation using ultrasound signals

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Research on biomedical engineering 2025年第2期41卷 1-16页

作者： Kauati, Adriana Cortela, Guillermo de Campos, Marcello L. R. Pereira, Wagner C. A. Programa de Pós-graduação em Engenharia Elétrica e Computação – CECE/UNIOESTE PR Foz do Iguaçu85870 650 Brazil Laboratorio de Acústica Ultrasónora – FCien/UdelaR Montevideo Uruguay Electrical Engineering Program – COPPE/UFRJ RJ Rio de Janeiro21941 - 914 Brazil Biomedical Engineering Program – COPPE/UFRJ RJ Rio de Janeiro21941 - 914 Brazil

Purpose: The article proposes an automated method for estimating mean scatterer spacing (MSS) in biological tissues using ultrasound signals. It employs singular spectrum analysis (SSA) with a novel entropy-based criterion to enhance accuracy and eliminate the need for manual parameter tuning. The method is validated using both simulated and real signals, demonstrating its effectiveness in detecting microstructural changes in tissues. Methods: The proposed SSA + entropy method estimates the MSS from ultrasound signals using SSA combined with a relative entropy-based criterion. This approach determines the optimal number of eigenvector pairs to reconstruct the periodic part of the signal by identifying the minimum in the entropy curve—a point that corresponds to the number of underlying periodic components, even in noisy conditions. For experimental validation, ex vivo bovine skeletal muscle was analyzed. RF data were collected at a controlled temperature of using a 3.5-MHz transducer. The MSS results obtained via SSA were also independently verified using microscopy and image analysis of muscle fiber spacing, confirming the effectiveness of the entropy-based SSA approach. Results: The MSS estimation method's accuracy decreases as jitter or Ad noise levels increase, with the method performing well when the estimated MSS is within 10% of the true value. Additionally, the standard deviation of MSS estimates increases as Ad levels and jitter values rise. In phantom experiments, MSS was measured using different transducer frequencies with varying results at each frequency. When applied to ex vivo bovine skeletal muscle tissue, the MSS estimation was validated using both RF and imaging methods, with three consistent groups of MSS values observed, confirming the method's applicability and reliability. Conclusion: The proposed method combines SSA and entropy to automatically estimate medium periodicity in ultrasound, eliminating the need for operator intervention. It succes

关键词： Image analysis

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Reports on Homeopathic therapy efficacy: A survey of two Brazilian newspapers

Reports on Homeopathic therapy efficacy: A survey of two Bra...

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Pan American Health Care Exchanges, PAHCE 2011 - Conference, Workshops, and Exhibits. Cooperation / Linkages: An Independent Forum for Patient Care and Technology Support

作者： Almeida, R.M.V.R. Biomedical Engineering Program COPPE UFRJ Rio de Janeiro Brazil

ISBN: (纸本)9781612849164

The objective of this work was to identify the existence of biases on the reporting of Homeopathy efficacy in Brazilian newspapers. To this end, the online archives of two large newspapers one in Rio de Janeiro city and one in So Paulo city were searched for all news or reports concerning Homeopathy in the period January 2009December 2010. The identified items were then classified as favorable, unfavorable or neutral in what concerns the efficacy of Homeopathic therapy. Paid advertisements and passing references were excluded. Thirty-one items were identified, and the results indicated an overall preponderance of favorable, as compared to unfavorable, reports (14 favorable, 7 unfavorable). In conclusion, newspaper reporting of homeopathic efficacy is not compatible with the most update scientific evidence on the topic. © 2011 IEEE.

关键词： Newsprint

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Conjunction of Bioelectrical Impedance Spectroscopy with Archie’s Law to Characterize Scaffolds Porosity 9th

Conjunction of Bioelectrical Impedance Spectroscopy with Arc...

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9th Latin American Congress on biomedical engineering, CLAIB 2022 and 28th Brazilian Congress on biomedical engineering, CBEB 2022

作者： Barbosa, Carlos Vinicius Nascimento de Souza, Marcio Nogueira Pino, Alexandre Visintainer COPPE/UFRJ/Biomedical Engineering Program Rio de Janeiro Brazil

ISBN: (纸本)9783031494000

Tissue engineering is a multidisciplinary field that uses two and three dimensional structures called scaffolds to create a physical support for growth, gas change and nutrition of the cell. Those scaffolds can be synthetic, biological or a combination of both types of material, but the porosity, the interconnectivity of pores and pore size are among the most important physical parameters of the scaffolds. The estimation of these characteristics is still a challenge in Tissue engineering, as it involves techniques and methods that need to be non-toxic and non-destructive, and that must operate in structures with dimensions of the order of micrometers (µm). The bioimpedance spectroscopy (bis) technique has been reported as a potential non-invasive monitoring of scaffold porosity and biological tissue growth. This work aims to study how bioimpedance spectroscopy in conjunction with Archiés law data can be used to characterize the porosity and pore connectivity of 3D cellular structures. © 2024, The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： Pore size

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Application of ShearWave™ Elastography to evaluate heat-induced changes in the Young’s modulus of fresh bovine muscle: a preliminary study

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Research on biomedical engineering 2021年第2期37卷 157-169页

作者： Costa-Júnior, José Francisco Silva de Oliveira, Viviane Bastos De Matheo, Lucas Lobianco de Albuquerque Pereira, Wagner Coelho Brazilian Air Force Academy PirassunungaSP Brazil Biomedical Engineering Program - COPPE Federal University of Rio de Janeiro Rio de JaneiroRJ Brazil

Purpose: The purpose of this study was to investigate the variation in the Young’s modulus (E) of bovine muscle samples as a function of temperature change generated by therapeutic ultrasound using ShearWave™ Elastography. Methods: Initially, the bovine muscle was heated via therapeutic ultrasound with a frequency of 3 MHz, nominal intensity of 2 W·cm−2, and application time of 2 min. Immediately following cessation of therapeutic irradiation, an E image was recorded and the stiffness was measured in circular area positioned at six depths (from 0.4 to 2.9 cm) in the center of the region of interest. Next, an E image was recorded every minute for the first 5 min. Over the next 30 min, an image was recorded every 5 min. Finally, an image was acquired 60 min after cessation of therapeutic irradiation. In the second test, the same experimental procedure was performed 60 min later with the physiotherapy equipment configured with a 10-min application time. Finally, during the ultrasonic irradiation of a new bovine muscle sample, the physiotherapeutic transducer was applied in a circular motion and with an angular velocity of 3.6 ± 0.3 rad·s−1. Results: In the first test, the bovine muscle E decreased from 212.2 ± 32.8 to 80.1 ± 13.8 kPa at 0.4-cm depth, as the temperature increased from 18.2 to 44.9 °C. This effect was reversed when the temperature decreased. In the second test, denaturation and cell death occurred, so an artifact appeared in the elastographic image and the ShearWave™ Elastography did not capture the E from the depth of 1.9 cm. Conclusion: We confirmed that it is possible to use ShearWave™ Elastography to investigate heat-induced changes in the elastic modulus of biological tissue. © 2021, Sociedade Brasileira de Engenharia Biomedica.

关键词： Cell death

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13th Mediterranean Conference on Medical and Biological engineering and Computing 2013, MEDICON 2013

作者： Da Silva, P.J.G. Rosa, B.P. Cagy, M. Infantosi, A.F.C. Biomedical Engineering Program/Coppe Federal University of Rio de Janeiro Rio de Janeiro Brazil

ISBN: (纸本)9783319008455

The coherent average was used for investigating the motion-related VEP (M-VEP). The electroencephalogram (EEG) signals of 29 healthy subjects were acquired during stabilometric protocol with distinct virtual scenes: static (SS) and dynamic (forward, DSF, or backward motion, DSB). The grandaveraged M-VEP for these visual conditions presented N2 peak dominance with higher values for parietal EEG derivation. The DS increased the N2 peak and latency, as well as the N2 - P3 amplitude, in comparison with SS. These components are not sensitive to motion orientation (t-test α = 0.05). However, the running t-test (α = 0.05) showed difference in the DSF - DSB waveforms 600 ms after the DS onset, with an increasing time delay from the occipital to central derivations. These findings suggest that the cognitive, planning and motor processing to maintain balance depends on the virtual scene direction. © Springer International Publishing Switzerland 2014.

关键词： Electroencephalography

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Dynamic visual stimulation effects on cortical response EEG desynchronization

Dynamic visual stimulation effects on cortical response EEG ...

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World Congress on Medical Physics and biomedical engineering

作者： Da Silva, P.J.G. Miranda De Sá, A.M.F.L. Infantosi, A.F.C. Biomedical Engineering Program / COPPE Federal University of Rio de Janeiro Rio de Janeiro Brazil

ISBN: (纸本)9783642293047

The time evolution of the event related desynchronization/synchronization index (ERD/ERS) was used for investigating the cortical activity effects of stimulating with virtual scenes. Occipital and parietal EEG leads of 29 healthy subjects were acquired during stabilometric test without and with visual stimulation (dynamic - DS;and static - SS virtual scene). Three EEG signal-processing procedures were used to analyze the ERD at the alpha peak frequency during the virtual stimulation, one of them excluding the EEG DS segment before normalization. This procedure decreased ERD index and hence 48.3 to 58.6% of subjects presenting cortical response after changing the virtual stimulation from the static to the dynamic scenes. The Wilcoxon test (α = 0.05) results indicate difference in the cortical response due to the EEG signalprocessing procedures (smaller percentage of ERD after excluding DS). These findings indicate the potentiality of the ERD/ERS assessment in studies of postural control during visual stimulation. © 2013 Springer-Verlag.

关键词： Virtual reality

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Breast ultrasound phantom for image segmentation assessment

Breast ultrasound phantom for image segmentation assessment

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2009 IEEE International Ultrasonics Symposium, IUS 2009

作者： De Carvalho, Isabela Miller Basto, Rodrigo Leite Q. Infantosi, Antonio Fernando C. Von Krüger, Marco Antonio Pereira, Wagner Coelho De A. Biomedical Engineering Program - COPPE Federal University of Rio de Janeiro Rio de Janeiro Brazil

ISBN: (纸本)9781424443895

Ultrasound (US) phantoms are used to simulate the main acoustic properties of human soft tissues and are usually applied in guided biopsy training and equipment calibration. In this work it is presented an ultrasound phantom that mimics breast lesions with regular shape, which is a typical feature related to non malignancy. The phantom matrix was made of a mixture of water, agar, glycerin and graphite and PVC powders and the lesions were of polyacrylamide. The mimicking properties were US attenuation, propagation speed and density. The regularity of the edge lesions was evaluated using two morphometric parameters: (1) Overlap Ratio (RS), and (2) Normalized Residual Mean square value (nrv). They were found compatible with regular contours of real lesions. ©2009 IEEE.

关键词： Ultrasonics

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U-Net and SegNet performances on lesion segmentation of breast ultrasonography images

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Research on biomedical engineering 2021年第2期37卷 171-179页

作者： Vianna, Pedro Farias, Ricardo de Albuquerque Pereira, Wagner Coelho Biomedical Engineering Program COPPE/Federal University of Rio de Janeiro Av. Horácio Macedo 2030 Room H327 Rio de JaneiroRJ Brazil Systems and Computing Engineering Program COPPE/Federal University of Rio de Janeiro Rio de JaneiroRJ Brazil

Purpose: Screening is the predominant strategy for the early detection of breast cancer. However, image analysis depends on the experience of the radiologist, inserting subjective factors in the evaluation of findings. Most biopsies performed on women with suspicious lesions on breast imaging tests show benignity. This medical technique is invasive and consumes time and resources;therefore, there is a demand to reduce these unnecessary procedures. Computer-aided diagnostics has been increasingly used as a second-reader tool lately, decreasing the diagnostic uncertainty of specialists. Based on this fact, the development of such systems is crucial and can be accomplished by the refinement of its steps, i.e., more accurate segmentation and classification. Considering this scenario, the present work describes the implementation of two well-known convolutional neural networks, U-Net and SegNet, for the segmentation of lesions found in breast ultrasonography. Defining which architecture is most appropriate for this task can ultimately help in reducing the number of biopsies performed. Methods: Convolutional neural networks are used in segmentation by classifying each pixel in an image, based on self-trained weights. Using a dataset of 2054 images, obtained in partnership with the National Cancer Institute, we compared the automatic segmentation performed by the networks with a manual segmentation made by a specialist. Results: Among the two proposed architectures, U-Net obtained better results in this task, obtaining a dice coefficient of 86.3%, and took 68.3% less training time than the SegNet, which achieved a dice score of 81.1%. Conclusion: The two networks can segment ultrasound images with useful accuracy depending on their configuration, with U-Net being faster to train and more accurate. © 2021, Sociedade Brasileira de Engenharia Biomedica.

关键词： Semantic Segmentation

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Comparative analysis of speech parameters for the design of speaker verification systems

Comparative analysis of speech parameters for the design of ...

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23rd Annual International Conference of the IEEE engineering in Medicine and Biology Society

作者： Souza, A.F. Souza, M.N. Biomedical Engineering Program COPPE Federal University of Rio de Janeiro Rio de Janeiro Brazil

Speaker verification systems are basically composed of three stages: feature extraction, feature processing and comparison of the modified features from speaker voice and from the voice that should be verified. Many features have been used in the first stage, although the current literature has not already shown the best of them. Based on the biometrics hypothesis, which states that each individual has a physical characteristic that distinguishes itself from the others, this paper realized a comparison between 12 classical widely used parameters, in order to investigate the biometrics hypothesis. The obtained results point out those parameters directly correlated to speaker's anatomy which are among the best ones that can be used in the development of speaker verification systems.

关键词： Area function Biometrics Speaker verification

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Effects of superimposed electrical stimulation training on vertical jump performance: A comparison study between men and women

Effects of superimposed electrical stimulation training on v...

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13th Mediterranean Conference on Medical and Biological engineering and Computing 2013, MEDICON 2013

作者： Costa, Denise da Conceição da Souza, M.N. Pino, A.V. Biomedical Engineering Program/COPPE Federal University of Rio de Janeiro Rio de Janeiro Brazil

ISBN: (纸本)9783319008455

Vertical jump height is a relevant feature in the assessment of muscle power;besides, jumps are essential in sports like volleyball, basketball and gymnastics. Training protocols combining Neuromuscular Electrical Stimulation (NMES) to voluntary contractions are valuable tools to improve jump height, although differences are expected according to gender. This paper aimed to evaluate the effects of a 4-week training protocol superimposing NMES to squats, into the vertical jump height of healthy, non-athlete men and women. Six women and eight men, age between 18 and 35, volunteered the study, being divided into groups according to gender, and subdivided into a group that would receive NMES and the control group. All the volunteers performed 5 series of 10 squats along the four weeks;a series of 10 Counter-Movement Jump and other of 10 Squat Jump were performed before and after the training protocol, in order to evaluate jump improvement. The results indicate that the superimposed training protocol improves men's jump height, although no results have been found for women. © Springer International Publishing Swit zerland 2014.

关键词： Sports

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